Transcriptome of Eriocheir sinensis under air exposure

Chinese mitten crab,Eriocheir sinensis,is an economically important crab in China.Air exposure is a common stress for E.sinensis,especially during the harvest a...     

干旱区内陆河流域的生态安全与生态需水量研究——兼谈塔里木河生态需水量问题

结合对干旱区生态安全和生态需水量关键科学问题的探讨,提出干旱内陆河流域生态脆弱区的生态安全分析是以水过程研究为核心的,水文过程控制着生态过程,对流域生态系统的稳定性有着直接影响,而水资源开发利用和水循环对生态系统功能有重要影响,天然植物恢复和生长的合理地下水位的研究是确立生态需水量的基础.并实证分析和计算了维系塔里木河生态安全的生态需水量,塔里木河干流现状生态需水量为31.74×108 m3,其中,上、中、下游分别为9.95×108 m3、18.47×108 m3和3.32×108 m3.     

The Representativeness of Air Quality Monitoring Sites in the Urban Areas of a Mountainous City

Lanzhou is a typical mountainous city with severe air pollution in northwestern China. This study uses hourly observational data of air pollutants at five air quality monitoring sites in Lanzhou from July to December 2015 to discuss data quality control and the representativeness of the monitoring sites(four urban sites and one suburban site). A fuzzy matrix is applied to study primary air pollutants. The results show that of the six routinely monitored pollutants,the primary pollutant is PM_10 during the study period. Based on lag correlation analysis and one-way analysis of variance, it is concluded that there are redundant observations at the four urban sites for the timely diffusion and transport of air pollutants from the same general area. The coefficient of divergence(COD) method is then used to evaluate the spatial distribution differences, and the primary air pollutant PM_10 shows differences at each site. COD can be used as a positive indicator to describe site representativeness. To evaluate the overall air pollution in the valley, correlation analysis is performed between the PM_10 concentration retrieved from aerosol optical depth satellite data and the concentration from the four urban monitoring sites. Among these, the correlation between the workers' hospital site data and the retrieval data is the highest, passing the 90% confidence level. A new representative evaluation model for air quality monitoring sites, R_s = 0.77 COD + 0.23R_(retrieval), is established by using COD and correlation coefficients between routine observations and satellite retrieval products. From this model, it can be concluded that the biological products institute site in Lanzhou is the most representative site for the evaluation of air pollution out of the four urban air quality monitoring sites from July to December 2015.     

Impacts of Land-Use Data on the Simulation of Surface Air Temperature in Northwest China

This study examines the impacts of land-use data on the simulation of surface air temperature in Northwest China by the Weather Research and Forecasting (WRF) model. International Geosphere–Biosphere Program (IGBP) landuse data with 500-m spatial resolution are generated from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite products. These data are used to replace the default U.S. Geological Survey (USGS) land-use data in the WRF model. Based on the data recorded by national basic meteorological observing stations in Northwest China, results are compared and evaluated. It is found that replacing the default USGS land-use data in the WRF model with the IGBP data improves the ability of the model to simulate surface air temperature in Northwest China in July and December 2015. Errors in the simulated daytime surface air temperature are reduced, while the results vary between seasons. There is some variation in the degree and range of impacts of land-use data on surface air temperature among seasons. Using the IGBP data, the simulated daytime surface air temperature in July 2015 improves at a relatively small number of stations, but to a relatively large degree; whereas the simulation of daytime surface air temperature in December 2015 improves at almost all stations, but only to a relatively small degree (within 1°C). Mitigation of daytime surface air temperature overestimation in July 2015 is influenced mainly by the change in ground heat flux. The modification of underestimated temperature comes mainly from the improvement of simulated net radiation in December 2015.     

主动学习与图的半监督相结合的高光谱影像分类

针对当前高光谱影像分类时,人工标注样本费时费力以及大量未标记样本未有效利用等问题,提出了一种主动学习与图的半监督相结合的高光谱影像分类方法。首先,将像素的光谱信息与其邻域内的空间信息相结合,利用重排序机制得到一种旋转不变的空谱特征表达。在此基础上,利用主动学习算法选择最不确定性样本(即分类模糊度最大的样本),提交操作者标注得到标记样本集。最后将该标记样本与未标记样本组合,用于图的半监督分类。该算法可保证类别边界样本的选择,利于分类器的边界构造,同时,在较少标记样本情况下,通过引入大量的未标记样本,可以达到较好的分类效果。在3幅真实高光谱影像上的试验表明,该方法可以取得精度较高的分类结果。     

MODIS/Terra observed snow cover over the Tibet Plateau: distribution, variation and possible connection with the East Asian Summer Monsoon (EASM)

Based on the snow cover fraction (SCF) data acquired from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the NASA Terra spacecraft from 2000–2006, statistical analyses are performed to explore the spatial and temporal distribution and variation of the snow cover over the Tibetan Plateau (TP). It is found that the snow persistence over the TP varies in different elevation ranges generally becomes longer with increases in the terrain elevation. In addition, the spatial distribution of the snow cover not only depends on the elevation but also varies with terrain features, such as aspect, slope, and curvature in the local areas. With 7-year observational data, seasonal and interannual variability of snow cover has been detected. There are slight decreasing trends in SFCs from 2000–2006. With MODIS satellite snow-cover fraction data and the National Centers for Environmental Predictions and U.S. Department of Energy NCEP/DOE reanalysis II dataset, the relationship between snow cover anomalies over the TP and the East Asian Summer Monsoon (EASM) is examined. Results indicate that the onset of the EASM is closely associated with snow cover anomalies in the spring. Specifically, a positive (negative) snow cover anomaly is followed by a later (earlier) onset of the EASM.     

雨雾、雪雾共生天气气象要素分析

利用多通道微波辐射计、边界层风廓线仪及自动/人工气象站等观测资料, 分析了2007年秋冬季北京地区雨雾和雪雾两次共生天气形成与维持过程中地面和高空气象要素伴随降雨、 降雪过程的变化。结果显示:(1) 高湿和小风是雨雾、雪雾生成并造成地面低能见度的主要气象条件。大雾形成与维持过程中, 地面水平能见度与相对湿度的反相关关系非常显著。能见度越低时, 雾的含水量也越高。 (2) 较弱的降雨和降雪可以促使雾含水量减少, 提高能见度, 但降雨或降雪蒸发增湿又利于雾的维持。 (3) 雨雾在降雨过程中高层气温经历大幅增降, 除可能受天气系统影响外, 与云层中水汽凝结释放的大量潜热和含水量大幅度增加也有关系。雪雾在降雪过程中高层温度总体随着时间趋于降低且变化幅度较小。 (4) 在降雨、降雪过程中雨雾和雪雾低层一直存在水汽饱和层, 且饱和层的顶部随降雨和降雪强度的加大而抬升, 厚度不断加大, 造成地面水平能见度进一步下降。结合催化剂人工消雾与共生雾降水 (降雨或降雪) 相似的原理, 个例分析结果初步表明较弱的降雨或降雪过程对消除暖雾、冷雾的影响有限, 对改善地面水平能见度并不显著, 这对人工消雾技术研究具有一定的启发作用。     

NUMERICAL EXPERIMENTS OF THE EFFECTS OF SEA SURFACE TEMPERATURE ANOMALIES OVER THE PACIFIC ON PRECIPITATION IN 1991*

A zonal domain,primitive equation model is used in this paper to study the influences of the main sea surface temperature anomaly(SSTA) areas over the Pacific on precipitation in 1991.Some numerical experiments are made and the mechanisms of the influences are discussed.The results show that the influences of the SSTA are mainly confined within the tropical and the subtropical regions.The direct effect of the SSTA is to change the exchanges of the sensible heat and the water vapour between the air and the sea,through the consequent changes of temperature and the flow fields and the feedback process of condensation,the SSTA finally affects precipitation.     

1991年缅甸7.6级地震的中长期预报及有关问题讨论

本文介绍了1991年1月5日缅甸7.6级地震的中期预报概况。主要依据是地震空区,震前2年在空区边缘发生一次6.2级地震后一个月内迅速形成300km长的地震条带,以及对大区域7级地震形势的综合分析。本文还着重讨论了6.2级地震后所形成的地震条带与未来大震之间的关系。     

臭氧和海温对夏季大气的影响机制

用球圈范围的Ｐ－σ坐标模式对Ｏ３和海温的影响进行了数值试验，第一种方案不包含Ｏ３，第二种包含了Ｏ３，第三种既包含了Ｏ３又引入了海洋混合层。结果表明，Ｏ３对大气的直接作用表现为高层大气的加热率增大，改变了１００ｈＰａ的气象场。间接作用则表现为Ｏ３引入促发了积云对流加热的变化，从而影响中、低层大气的加热率。海洋混合层的影响是直接的，主要通过海面感热和蒸发量的变化影响低层大气。